During the latter stages of building construction, many of the materials to be used must be transported into the uncompleted building shell. This is typically done by hand carrying such materials from the delivery site immediately outside the building and passing the materials through a roughed in (i. e., with no window glass, sash, etc. installed) window opening or doorway. Often, due to interior walls, it is more expeditious to pass the materials through a window opening rather than through an exterior doorway and intervening interior doorways.
This leads to potential problems, particularly with relatively heavy but fragile building materials such as drywall sheets or boards, also known as gypsum wallboard. Drywall sheet is typically manufactured in sheets measuring four feet wide by eight to sixteen feet long in several thicknesses, and packaged in bundles of two sheets each. Sheets of greater thickness are relatively heavy, weighing 115 to 290 pounds per bundle. Yet the material itself is relatively soft and frangible and can be easily dented or broken. When passing such materials through roughed in window openings, great care must be used in order to prevent damage from occurring to the edges of the drywall sheets as they come in contact with the relatively rough wood or other material of the window opening. If a finished frame has been installed in the window opening, even greater care must be exercised in order to prevent damage to the finished frame. This results in a great deal of stress for the workers handling the sheets, due to the necessity of supporting the sheets so as to prevent damage to them from scraping them on the window opening. This particular task of building construction has led to back and other injuries to workers involved in transferring such materials into an uncompleted building shell, even though often the materials are transferred directly from a truck lifting boom to a point immediately outside the opening in the building shell.
Furthermore, it is sometimes necessary to transfer such drywall sheets from one level to another up a flight of stairs. In order to prevent damage to the sheets, it is necessary for a worker or workers to carry the sheets up the stairs in order to prevent contact with the edges of the step treads. A single worker or even two workers are limited in the number of sheets they can carry due to the relatively large size and weight of the sheets.
The need arises for a device which may be quickly and easily installed upon a window or similar opening in a building, which may be used to support drywall sheets or other relatively heavy, bulky materials as they are passed through such an opening into the building interior. The device should be easily removable and also easily adaptable for use on stairways or the like so such drywall sheets or other materials may be supported by the device rather than being carried and completely supported by a worker. The device should offer a relatively low friction surface on which the building materials may be supported and slid for transfer.